On 07/24/2018 12:36 AM, Ingo Molnar wrote:
>
> * Dan Williams <dan.j.williams@xxxxxxxxx> wrote:
>
>> In preparation for using set_memory_uc() instead set_memory_np() for
>> isolating poison from speculation, teach the memtype code to sanitize
>> physical addresses vs __PHYSICAL_MASK.
>>
>> The motivation for using set_memory_uc() for this case is to allow
>> ongoing access to persistent memory pages via the pmem-driver +
>> memcpy_mcsafe() until the poison is repaired.
>>
>> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
>> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
>> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
>> Cc: Tony Luck <tony.luck@xxxxxxxxx>
>> Cc: Borislav Petkov <bp@xxxxxxxxx>
>> Cc: <linux-edac@xxxxxxxxxxxxxxx>
>> Cc: <x86@xxxxxxxxxx>
>> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
>> ---
>> arch/x86/mm/pat.c | 16 ++++++++++++++++
>> 1 file changed, 16 insertions(+)
>>
>> diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
>> index 1555bd7d3449..6788ffa990f8 100644
>> --- a/arch/x86/mm/pat.c
>> +++ b/arch/x86/mm/pat.c
>> @@ -512,6 +512,17 @@ static int free_ram_pages_type(u64 start, u64 end)
>> return 0;
>> }
>>
>> +static u64 sanitize_phys(u64 address)
>> +{
>> + /*
>> + * When changing the memtype for pages containing poison allow
>> + * for a "decoy" virtual address (bit 63 clear) passed to
>> + * set_memory_X(). __pa() on a "decoy" address results in a
>> + * physical address with it 63 set.
>> + */
>> + return address & __PHYSICAL_MASK;
>
> s/it/bit
Thanks Ingo! I'll update when I pull in the patch.
>
> Thanks,
>
> Ingo
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